The present invention relates to a solid electrolytic capacitor and a method of manufacturing the capacitor.
Electronic equipment, such as a personal digital assistant, is recently required to be smaller and to have a high performance, and it has been accordingly demanded that electronic components have high performance in small bodies. A solid electrolytic capacitor placed in a secondary side of a power circuit, or close to a central processing unit (CPU) of a personal computer is required to have a large capacitance in a lower profile and a lower equivalent series resistance (ESR) as well as a lower equivalent series inductance (ESL). To reply to the requirement, various studies, such as surface condition of the anode, a method of forming dielectric layer, development of and improvements in a solid electrolyte layer, and the structure of a capacitor element have been carried out.
FIG. 16 is a sectional view of a conventional solid electrolytic capacitor. Dielectric layer 4 is formed of foil or sintered material 2 made of valve metal, such as tantalum, aluminum, and niobium, by anodization. Solid electrolyte layer 5 formed of oxide of transition metal, such as Mn, is formed on the surface of dielectric layer 4. Collector layer 6 is formed on the surface of solid electrolyte layer 5. Anode lead frame 8 is connected with lead portion 1 of an anode, while cathode lead frame 9 is connected with collector layer 6. The capacitor is covered with housing resin 7 to have anode lead frame 8 and cathode lead frame 9 exposed.
Since including the lead frames, the conventional solid electrolytic capacitor hardly includes a large volume of the anode for a large capacitance and hardly has a small ESR and a small ESL.
A capacitor includes a valve metal foil including a valve metal porous body and a lead portion, a dielectric layer provided on the valve metal porous body, a solid electrolyte layer on the dielectric layer, a collector layer on the solid electrolyte layer, an anode lead connected to the lead portion, a housing for accommodating the valve metal porous body, the dielectric layer, the solid electrolyte layer, the collector layer, and the anode lead, and for having an end of the anode lead exposed from a surface of the housing, an anode external terminal provided over the housing and connected with the end of the anode lead, and a cathode external terminal provided over the housing and coupled with the collector layer. The capacitor has a large capacitance, a small ESR, and a small ESL.